In what month and year did Facebook reach 1 billion monthly active users?

Facebook reached 1 billion monthly active users in October 2012. Mark Zuckerberg announced the milestone at the beginning of that month, marking Facebook’s arrival at a scale few internet services had achieved.

The milestone referred to monthly active users, meaning people counted as active within a month—not necessarily unique people using Facebook every day. At the time, Facebook also reported about 600 million mobile users, showing how quickly usage was shifting from desktop computers to phones.

Facebook had passed 100 million registered users in 2008 and 500 million in July 2010. Reaching 1 billion monthly active users just two years later reflected the platform’s international growth and expanding mobile reach.

The date is sometimes confused with the exact announcement day, October 4, 2012, or with later user milestones. The quiz asks for the month and year, making October 2012 the canonical answer.